Laser-induced thermal transfer processes are well-known imaging processes used in applications such as color proofing, electronic circuit manufacture, color filters, lithography, and other areas. Such laser-induced processes include, for example, dye sublimation, dye transfer, melt transfer, and ablative material transfer. These processes have been described in, for example, Baldock, U.K. Patent 2,083,726; DeBoer, U.S. Pat. No. 4,942,141; Kellogg, U.S. Pat. No. 5,019,549; Evans, U.S. Pat. No. 4,948,776; Foley et al., U.S. Pat. No. 5,156,938; Ellis et al., U.S. Pat. No. 5,171,650; and Koshizuka et al., U.S. Pat. No. 4,643,917.
Laser-induced processes use a laserable assemblage comprising (a) a donor element that contains a donor layer comprising a material to be transferred (for example a colorant such as a dye, a pigment, or a pigmented layer), and (b) a receiver element having a receiving surface, that are in contact. The laserable assemblage is imagewise exposed by a laser, usually an infrared laser, resulting in a transfer of the material from the donor layer of the donor element to the receiver element, on or through its receiving surface. Each imagewise exposure takes place only in a small, selected region of the laserable assemblage at one time, so that the transfer of the material from the imageable element to the receiver element can be built up one pixel or region at a time. Computer control accomplishes the transfer with high resolution and at high speed. The laserable assemblage after the imagewise exposure to the laser as described supra, is henceforth termed an imaged laserable assemblage.
The imaged laserable assemblage can be separated into two elements, (c) a thermally imageable element containing material in unexposed regions, and (d) an imaged receiver element containing the transferred material from exposed regions. The imaged receiver element can be incorporated as above into a new laserable assemblage in order to imagewise transfer other material in a subsequent, often different, imagewise exposure. Such a repeated process can produce an imaged receiver element incorporating many different materials, which have been imagewise transferred using different assemblages. The different materials may each comprise a colorant, for example to produce a multicolor proof or a color filter. An imaged receiver element can by itself be regarded as a multi-element assemblage comprising a receiving layer and transferred materials, which can be useful as a color proof, color filter, or printing plate. However, in many cases an imaged receiver element is incorporated with other elements or materials by well known techniques to produce a final assemblage, e.g. a color proof, color filter, or printing element.
Laser induced thermal imaging processes and products, which utilize a receiver element, are described in U.S. Pat. No. 6,294,308 of Caspar, et al., U.S. Pat. No. 5,834,154, of Yamazaki et al., and U.S. Pat. No. 6,316,385 of Usuki, et al. Caprolactone polymers are used in receiver elements in U.S. Pat. No. 6,294,308.
U.S. Pat. No. 5,834,154, concerns a thermal transfer image-receiving sheet comprising a substrate sheet, a dye-receptive layer provided on at least one surface of the substrate sheet, and a backing layer provided on the other surface of the substrate sheet, wherein the dye-receptive layer contains polycaprolactone.
U.S. Pat. No. 6,316,385 discloses a thermal transfer dye image-receiving element that is said to form high-quality color images by a thermal transfer method. The disclosed thermal transfer dye image-receiving sheet comprises: a substrate sheet; and a dye-receptive layer provided on at least one side of the substrate sheet, the dye-receptive layer containing at least a modified polymer, namely a caprolactone-modified cellulose, the cellulose including a cellulose acetate component.
Compatibility of polymer blends is a highly complex field, and results are often difficult to predict. Performance characteristics in polymer blends, such as releasability, bleeding, durability, adhesivity, blocking, compatibility with adhesives, and clarity, clearness, or transparency, often must be empirically determined. However, polymer blends can be preferable over modified polymers because of availability, ease of variation to obtain desired properties, low price, or due to knowledge of desirable characteristics of each component in the polymer blend, such as low toxicity of the components of the polymer blend, in contrast to unknown or less well-known characteristics of a newer modified polymer.
It is important that the imaged receiver element be durable to the normal handling necessary to produce a final product, such as incorporation in multiple laserable assemblies, or lamination onto a permanent carrier.
It is desirable to use the imaged receiver element directly as, or incorporated into, a final product such as a color proof, color filter, or printing plate, in which the final outermost surface is exposed to the environment. It is important that the final outermost surface be durable and resistant to blocking during handling and use, for example if the final product is stacked and unstacked, held and released, or used in a printing process. In many cases it is useful for the final outer surface to be sufficiently transparent to allow viewing of, or the projection of light through, any colored materials which were imagewise transferred onto the receiver, for example to form a color proof or color filter.